The present invention relates to a light exposure lamp control circuit and, more particularly, to an abnormal condition monitor for monitoring the condition of a light exposure lamp by monitoring the detection of a light amount sensor for detecting the light amount of a light scanning lamp in a light scanning device for an electrophotographic copying machine, an image scanner, or a facsimile machine.
Tradionally, electrophotographic copying machines are equipped with automatic light exposure-amount control devices for automatically controlling the amount of light exposure for scanning the face of an original, in accordance with the brightness of the face of the original. As the black portions of the original images increase, the overall darkness of the original also increases. With such an automatic light-exposure-amount control device, regardless of the darkness of the original, a constant of copied paper can be enabled. However, a correct light exposure may not be achieved in the case where the light scanning lamp has deteriorated, or the light control means becomes absormal.